细沟侵蚀阶段玉米季坡耕地氮素流失特征

研究紫色土区坡耕地玉米全生育期细沟侵蚀阶段水土及氮素流失规律,以期为研究区氮素流失有效防控提供科学依据。采用人工模拟降雨与野外径流小区相结合的方法,开展降雨强度为1.5mm/min条件下玉米全生育期细沟侵蚀阶段地表径流、壤中流和侵蚀泥沙中氮素流失特征的研究。结果表明:细沟侵蚀阶段,玉米各生育期地表径流量、壤中流量和侵蚀产沙量总体表现为随降雨时间延长呈先增加后平稳的变化趋势。地表径流中总氮、可溶性总氮、硝态氮和侵蚀泥沙中总氮流失量总体呈现先增加后平稳的趋势,而地表径流中铵态氮流失量变化趋势在降雨前期呈现波动性变化,降雨后期逐渐平稳。壤中流中总氮、可溶性总氮、硝态氮、铵态氮流失量则随着降雨时间延长呈现平稳的变化趋势。细沟侵蚀阶段地表径流中氮素流失总量在玉米苗期最大,为628.77mg/m2;壤中流中氮素流失总量在拔节期和抽雄期最大;侵蚀泥沙中氮素流失总量在苗期最大,为144.95mg/m2。壤中流为氮素流失主要途径,硝态氮为氮素流失主要形态。

Characteristics of Nitrogen Loss in Sloping Farmland in the Whole Maize Growth Periods During Rill Erosion Stage

In order to effectively prevent and control nitrogen loss in the growth stages of maize in the purple soil area during rill erosion stage, the soil erosion and nitrogen loss was studied. The artificial simulated rainfall combined with field runoff plot experiments were used to study the characteristics of nitrogen loss, including surface runoff, interflow and sediment yield, soil flow and erosion sediment, in the whole stages of maize during rill erosion stage under the rainfall intensity of 1.5 mm/min. The results showed that surface runoff, interflow and sediment yield were increased first with rainfall duration, and the values tended to peak during maize growth stages at rill erosion. Total nitrogen, soluble total nitrogen, nitrate and sediment yield in surface runoff showed an overall trend of first increase and then stability, while ammonium nitrogen loss showed volatility in the early rain period and became steady gradually with rainfall duration. The total nitrogen losses in surface runoff were the highest at seedling stage of maize, and the maximum was 628.77 mg/m². The total nitrogen losses in interflow were the highest at jointing stage and tasseling stage of maize. The total nitrogen losses in sediment yield were the highest at seedling stage of maize, and the maximum was 144.95 mg/m².Interflow were the main channels for nitrogen losses, and nitrate nitrogen was the main form of nitrogen loss during the rainfall process.